1. Technical Field
This application relates to plot handlers for pen plotters and the like and, more particularly, in a plot rolling mechanism for a pen plotter or the like having a rolling mechanism with an entry opening and a receiving bin for receiving rolled plots, to the improvement comprising, a sealing mechanism for sealing the entry opening during plotting, the sealing mechanism being rotatable between a sealing position blocking the entry opening and a retracted position not blocking the entry opening; and, means for rotating the sealing mechanism between the sealing position and the retracted position. It also relates to the improvement of the receiving bin having a horizontal slot opening across the width adjacent a top edge thereof, the slot opening being of a height and width sufficient to pass a largest rolled plot therethrough; and, a flap hinged adjacent the top edge and extending over the slot, the flap having a weight sufficient to maintain it over the slot under normal use and light enough to deflect and open the slot under the weight of the lightest rolled plot expected when a rolled plot entering the receiving bin is rolling off a maximum number of allowed rolled plots already in the receiving bin.
2. Background Art
Pen plotters are popular so-called peripheral devices for use with computers, particularly in conjunction with applications programs such as CAD/CAM. They have an advantage over other forms of plotting of being simple in operation and construction and, therefore, lower in price. As shown in simplified form in FIG. 1, a basic pen plotter 10 after drawing the plot on the media 12 may simply move the media 12 over a support table 14 by means of a pinch roller 16 holding the media 12 against a driven drum 17 to eject the completed plot into a receiving bin 18. With large plot sheets, the completed plot can wrinkle and cause problems and poor print quality when later reproduction by a diazo process, or the like, is attempted. Attempting to roll the randomly-folded plot onto a old media roller for safe-keeping is a time-consuming and often frustrating process.
In more complex and costly devices such as electrostatic printers and plotters, a media rolling apparatus is sometimes included as part thereof. Such prior art attempts, are large and expensive and, typically, incorporate a lot of surface area over which the moving media must be moved again the friction imposed thereby. Overcoming the frictional considerations adds to the complexity and cost of the apparatus.
A prior invention assigned to the assignee of this application is disclosed in U.S. Pat. No. 5,177,497 which issued 5 Jan. 1993. The apparatus of that patent and its manner of construction and operation is shown in FIGS. 2 through 4. The rolling mechanism 20 of that invention is intended to be mounted between the ejection point 22 and the receiving bin 18 in a pen plotter 10 such as that depicted in simplified form in FIG. 1. The exact placement and the specific shape of the components are, of course, a function of the pen plotter 10 into which the rolling mechanism 20 is incorporated.
Starting with the mechanism 20 in its open position as depicted in FIG. 4, there is a stationary portion 24 and a rotating portion 26 which is mounted on and rotates in combination with the shaft 28. The stationary portion 24 comprises a first input guide portion 30 connected to a first partially-cylindrical portion 32. Thus, as the media 12 moves along its exit path, it moves over the input guide portion 30. A single, horizontal, cylindrical drive roller 38 is disposed behind the input guide portion 30 in the center thereof and extends through a slot 40 provided in the supporting structure of the first input guide portion 30 for the purpose. Because of the low friction environment of the invention, one drive roller 38 in the center is sufficient, but several across the width of the media could be employed if desired.
The rotating portion 26 comprises a second input guide portion 48 connected to a second partially-cylindrical portion 50. The second input guide portion 48 carries a free-wheeling roller 39 positioned to mate with the drive roller 38 with the media 12 therebetween. The two partially-cylindrical portions 32, 50 are pivotally joined at the location of the shaft 28. The shaft 28 is bi-directionally rotated by any appropriate drive mechanism 52 under the control of the logic 46 to rotate the rotating portion 26 between the open position of FIG. 4 and the closed position of FIG. 3.
In operation, with the mechanism 20 in its open position, the drive rollers 38 are inactivated. Upon the leading edge of the media 12 having entered the rolling mechanism 20 to a point below the drive rollers 38, the logic 46 activates the drive mechanism 52 to rotate the rotating portion 26 to the closed position of FIG. 3.
As can be seen in FIG. 3, in the closed position the two input guide portions 30, 48 form a guide slot 54 extending into a cylindrical rolling chamber 56 formed by the two partially-cylindrical portions 32, 50. The drive rollers 38 are pressed lightly against the free-wheeling rollers 39 with the media 12 therebetween. The rotating portion 26 is maintained in the closed position of FIG. 3 by the drive mechanism 52. When the rotating portion 26 is in the closed position of FIG. 3, the logic 46 activates the drive mechanism 60 which is connected to rotate the drive rollers 38. The drive rollers 38 then gently urge the media 12 forward through the guide slot 54 into the cylindrical rolling chamber 56 where it is smoothly rolled. When the logic 46 recognizes that the trailing edge of the media 12 has been reached, the logic 46 stops the drive mechanism 60 and activates the drive mechanism 52 in the opposite direction to open the rotating portion 26 to the open position of FIG. 4 whereupon the smoothly and neatly rolled media 12' falls into a receiving bin 18.
While the apparatus of FIGS. 2-4 works well for its intended purpose, there are several aspects which can be improved for various reasons. For example, the moving end of the media 12 may enter the guide slot 54 during the plotting process and become fouled in the mechanism. The receiving bin 18 may also become over-filled and back up relied media 12' into the rolling mechanism 20.
Wherefore, it is an object of the present invention to provide a way to prevent the moving end of the media from entering the guide slot during the plotting process.
It is another object of the present invention to provide a way to prevent the receiving bin from becoming over-filled and backing up rolled media into the rolling mechanism.
Other objects and benefits of this invention will become apparent from the description which follows hereinafter when read in conjunction with the drawing figures which accompany it.